Jinny,
Yes, that is correct. An even bigger shift is for C in
carbonates. That is why fluorite should not be used as a F standard
for silicates (we use F-topaz). There are protocols for correcting
this effect that are described in Goldstein et al., and which have
been modified by John Donovan for direct analysis of O in oxides and
silicates. Anyone analyzing second row elements ("ultralight
elements" in EMP parlance) with emission of characteristic X-rays has
to address this problem.
The shift in Fe La has been used to estimate Fe3+/Fe2+ in oxides
(e.g., paper by Nash) although there are serious questions about the
reliability of that measurement applied to solid solutions. Even S
Ka has a big shift between sulfates and sulfides, which is well known
to igneous petrologists, who use the effect to judge the type of S
found in silicate glass. There is a paper by Lovering et al. (1970±)
who used the shift in S Ka to determine the valence of S in micas.
eric
>Another factor to consider is that the type of bonding will affect
>the peak position of light elements. There is quite a shift in
>position for C between graphite, diamonds and the various fullerenes.
>Chemists in nanotechnology will sometime use this to identify which
>carbon phase is being analyzed. There is also a peak shift for B
>that will affect any analysis.
>
>Jinny
>--
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